Collaborative Research: Dynamics and Predictability of Tropical Weather and Climate through Cloud-resolving Ensemble Assimilation of Sounding and Radar Observations from DYNAMO

麦登-朱利安涛动（MJO）是热带大气在季节内时间尺度上的主导模式，对全球天气和气候的许多方面都有重大影响。虽然MJO的基本特征已被多年的观测揭示，但其潜在的动力学仍然知之甚少，目前的数值天气和气候模式在模拟和预测MJO事件方面技能较低。最近完成的nsf赞助的Madden-Julian振荡动力学（DYNAMO）现场活动针对的是与印度洋MJO形成关键相关的过程。该拨款旨在利用基于天气研究和预报（WRF）模型的基于集合的数据同化（EnDA），通过吸收DYNAMO期间收集的雷达、探空和卫星观测数据，探索热带天气和气候从对流到季节内尺度的动态和可预测性。对研究特别感兴趣的DYNAMO观测是来自三个多普勒雷达的观测，以及来自一个增强的中尺度探测网络的观测。主要研究目标包括：(1)通过比较不同的变分同化、集合同化和混合同化方法，探索从对流尺度到区域尺度热带天气分析和预报的最可靠和有效的EnDA方法；(2)在整个DYNAMO期间，采用最准确、最经济的EnDA方法进行对流尺度和区域尺度的再分析，并通过定期和实地观测以及现有的全球分析或再分析进行验证；(3)利用对流允许的（即非常高的时空分辨率）集合分析和预报，研究热带天气和气候（包括MJO）从对流到季节内尺度的动态和可预测性。知识优势：EnDA技术与实地观测的结合在数据同化方面构成了潜在的重大进步，并使我们对热带天气和气候从对流尺度到季节内尺度的动力学、演变、预测和可预测性的理解有所提高。分析和预报还为从对流尺度到季节内尺度对热带天气和气候的理解提供了有效的途径。更广泛的影响：通过博士研究生和博士后科学家的广泛参与，研究工作将提供教育效益。研究成果也将直接用于课堂教学和指导本科生的研究项目。关于MJO事件的初始化、预测和可预测性的研究结果将改善热带天气和气候的业务预报，为公众提供直接利益，无论他们生活在热带地区还是世界上受MJO事件影响的地区。在这种支持下开发的EnDA系统，以及通过WRF模拟对DYNAMO观测结果的再分析，将在网上免费提供，并提供充足的文件，以使更大的学术界受益。

The Madden-Julian Oscillation (MJO), which is the dominant mode of the tropical atmosphere at intraseasonal time scales, has significant impacts on many aspects of weather and climate across the globe. While the basic features of the MJO have been revealed by observations for many years, its underlying dynamics remain poorly understood and current generation numerical weather and climate models have low skills in simulating and predicting MJO events. The recently completed NSF-sponsored Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign targeted processes critically related to MJO initiation in the Indian Ocean.This grant seeks to use ensemble-based data assimilation (EnDA) based on the Weather Research and Forecasting (WRF) model to explore the dynamics and predictability of tropical weather and climate from convective to intraseasonal scales by assimilating radar, sounding, and satellite observations collected during DYNAMO. The DYNAMO observations of particular interest to the research are those from three Doppler radars, and those from an enhanced mesoscale sounding network. Major objectives of the research include: (1) exploring the most reliable and effective EnDA methods for tropical weather analysis and forecasts ranging from convective to regional scales by comparing different variational, ensemble-based and hybrid data assimilation approaches; (2) conducting convective- and regional-scale reanalysis using the most accurate and affordable EnDA method over the entire DYNAMO period, and verify with regular and field observations as well as existing global analysis or reanalysis; and (3) examining the dynamics and predictability of tropical weather and climate (including the MJO) from convective to intraseasonal scales using convection-permitting (i.e., very high temporal and spatial resolution) ensemble analysis and forecasting.Intellectual merits: The combination of the EnDA technique with field observations constitutes a potentially significant advance in data assimilation, and our understanding of the dynamics, evolution, prediction, and predictability of tropical weather and climate from convective to intraseasonal scales. The analysis and forecasts also provide an efficient pathway to bridge the understandings of tropical weather and climate from convective to intraseasonal scales.Broader impacts: The research efforts will provide educational benefits through the extensive participation of a doctoral graduate student and a postdoctoral scientist. Research findings will also be directly used in classroom teaching and for directing undergraduate research projects. The findings on the initialization, prediction, and predictability of MJO events will improve operational forecasts of tropical weather and climate, providing a direct benefit to the general public, whether they live in the tropics or in areas around the world that are affected by MJO events. The EnDA systems developed from this support, and the reanalysis of DYNAMO observations by WRF simulations, will be made freely available online with ample documentation to benefit the larger academic community.